Well the Patriots were pretty bad in the 70s.
And in the 70s the Flyers ruled Philadelphia as well, even the blacks became fans of The Broad Street Bullies.
It was a different time.
Visit https://www.pro-football-reference.com/teams/nwe/ and scroll down through the season by season log and you'll see seasons in the '70s where the Patsies went 7-7, 9-5, 11-3, and 11-5 (also a 2-12 and a 3-11).
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And won their first Cup at the expense of the Broons' who were trying for their 3rd Cup in 5 years after not winning one for 29 years prior to that run.